Table 2. Assignment of frequency to chemical functions.

Frequency (cm−1)	Chemical function
∼3500	O-H stretch of hydroxyl groups
∼3200	N-H stretch ( Amide A) of proteins
∼3000–3060	C = C stretch
∼2955	C-H asymmetric stretch of –CH3 in fatty acids
∼2930	C-H asymmetric stretch of –CH2
∼2918	C-H asymmetric stretch in fatty acids
∼2898	C-H symmetric stretch of C-H in methyl groups
∼2870	C-H symmetric stretch of –CH3
∼2850	C-H symmetric stretch of –CH2 in fatty acids
∼1740	-C = O stretch of esters
∼1715	-C = O stretch of carbonic acids
∼1680–1710	-C = O in nucleic acids
∼1695	Amide I band components of proteins
∼1685	Antiparallel pleated sheets
∼1675	Resulting from β- turns of proteins
∼1655	Amide I of α-helical structures
∼1635	Amide I from β-pleated sheet structures
∼1575	Asymmetric stretch of COO-
∼1550–1520	Amide II
∼1515	“Tyrosine” band
∼1468	C-H deformation of –CH2
∼1400	C = O symmetric stretch of COO-
∼1310–1240	Amide III band components of proteins
∼1250–1220	P = O asymmetric stretch of PO2 − phosphodiesters
∼1200–900	C-O; C-C; C-O-H; C-O-C deformation of carbohydrates
∼1090–1085	P = O symmetric stretch of PO2 −
∼720	C-H rocking of –CH2
∼900–600	“ Fingerprint region”

From [19], [20].